1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to jam recovery when a paper jam (jam, hereinafter) occurs.
2. Description of the Related Art
In a conventional image forming apparatus such as a copying machine, a facsimile machine and a laser beam printer, there is an apparatus which forms an image on a sheet by an electrophotographic system. According to such an image forming apparatus, when an image is formed on a sheet, a photosensitive drum is exposed according to image information to form an electrostatic latent image on the photosensitive drum. Next, the electrostatic latent image is developed by toner in a development device, and visualized as a toner image, and the toner image is transferred to a sheet which is fed from a sheet feeding portion. Thereafter, the sheet is conveyed to a fixing nip of a fixing roller and a pressure roller provided on a fixing portion by a pre-fixing conveying portion, and the image is fixed to the sheet as a permanent image.
As such conventional image forming apparatuses, there is one in which a transfer member constituting a transfer portion, the pre-fixing conveying portion and the fixing portion are unitized as a pull-out unit, and the pull-out unit is pulled out from a front surface of an apparatus body. This technique is disclosed in Japanese Patent Laid-Open No. 2007-052276. By pulling out the pull-out unit in this manner, it is possible to easily carry out the jam recovery in the sheet conveying passage and maintenance of the apparatus.
However, in such a conventional image forming apparatus, the jam occurs not only in the pull-out unit, but also in a state where a sheet is jammed between the pull-out unit and an upstream sheet conveying passage through which the sheet is conveyed to the pull-out unit.
When a sheet jam occurs between pull-out unit and the upstream sheet conveying passage, the pull-out unit can be pulled out only after the upstream sheet conveying passage is opened and the jammed sheet is removed. This is because that if the pull-out unit is pulled out when a sheet exists between the pull-out unit and the upstream sheet conveying passage, there is an adverse possibility that the sheet is caught in a body frame and the sheet is torn. For this reason, it is necessary to open the upstream sheet conveying passage, but a complicated mechanism and a space for opening the sheet conveying passage are required, and there is an adverse possibility that cost of the apparatus is increased and an installation space for the apparatus is also increased in size.